Solar energy is an inexhaustible regenerative energy source. Today when the energy situation is so severe, development and utilization of solar energy is one of the important ways to realize a multiple-channel energy supply and to ensure security in the energy supply.
Among the great many forms of solar energy utilization, the thermal tower power generation device is undoubtedly a technical device with great competitiveness. Experiments and research conducted in developed countries has proven that solar thermal power generation is effective for large scale industrialized application. Therefore, energetic development of solar thermal power generation may not only provide us with good clean energy, but may also start the growth of a newly rising industrial group, and may even bring a revolutionary solution to the tense energy problem. Its basic principle is to use a large number of heliostats to reflect the radiated solar energy onto the solar receiver mounted on the top of a high tower, where the medium is heated or the water in the heat collector is directly heated to produce superheated gas, to drive a gas turbine or steam turbine generator to generate electricity, thus converting solar energy into electric energy.
The high temperature solar receiver is the core component of a tower thermal power generation system. Research has been conducted on this technology in a number of countries, mainly in Spain, Israel and the United States. High temperature solar receivers are roughly in two forms: external light receiving type and volumetric. Compared with the latter, the former obviously has higher heat loss, while the latter requires no selective absorbing coating for solar energy under high temperature. The present trend of development of volumetric receivers is that the medium temperature parameter is increasing continuously, making it more suitable to the modern gas turbine—generator cycle with a high temperature parameter. We can sum up the technical plans of typical volumetric receivers as follows: in most existing technical plans, a single-layer quartz glass hood is used as the window to transmit sunlight, (this is clearly described in U.S. Pat. Nos. 5,421,322, 6,516,794 and 5,323,764); secondly, the working fluid passage is designed in various forms on the basis of the heat transfer principle, to minimize the resistance, to homogenize the working fluid, to reduce the heat loss as much as possible, and to reduce local overheating and stress resulting from thermal expansion. They have the following drawbacks. First, with a single-layer quartz glass hood as the window to transmit sunlight, it is in direct contact with the working fluid under high temperature and high pressure. Although it is possible for cold working fluid to flow along the surface wall of the glass hood in the flow design of the fluid, the actual flow conditions of fluid would be much more complicated than those designed and envisaged, and the expected result cannot be fully met. Therefore, a local high temperature may develop on the glass hood, making it likely to crack or break. Second, the single-layer quartz glass hood will be at a high temperature. Therefore, cold fluid must be used to cool it in the design. The plan proposed in U.S. Pat. No. 5,421,322 is to admit cold fluid respectively on the inner and outer walls of the glass hood. However, when the fluid entering from the light incident end flows along the glass outer wall, the heat will be carried away by the fluid, and it would be very difficult to make full use of the fluid thus heated. Therefore, although it has cooled the glass hood, it does not favor increase of heat efficiency. Third, a more outstanding issue is that most receivers can only absorb heat, while the heat reservation function required when there is insufficient sunlight is provided by a separate heat reservation device, not as part of the receiver.